CN116282012A - Method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction, high-proportion microporous activated carbon and application thereof - Google Patents
Method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction, high-proportion microporous activated carbon and application thereof Download PDFInfo
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- 238000000605 extraction Methods 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 25
- 239000002994 raw material Substances 0.000 claims abstract description 98
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- 238000001035 drying Methods 0.000 claims abstract description 48
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- 238000005406 washing Methods 0.000 claims abstract description 34
- 238000002156 mixing Methods 0.000 claims abstract description 31
- 238000001179 sorption measurement Methods 0.000 claims abstract description 30
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- 239000003513 alkali Substances 0.000 claims abstract description 14
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- 239000003795 chemical substances by application Substances 0.000 claims abstract description 9
- 238000010438 heat treatment Methods 0.000 claims description 34
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 26
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- 239000000047 product Substances 0.000 claims description 21
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- 238000003756 stirring Methods 0.000 claims description 20
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- 238000004519 manufacturing process Methods 0.000 claims description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 4
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- 238000007689 inspection Methods 0.000 claims description 4
- 238000005119 centrifugation Methods 0.000 claims description 3
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 2
- 239000011148 porous material Substances 0.000 abstract description 45
- 239000002028 Biomass Substances 0.000 abstract description 18
- 229910052799 carbon Inorganic materials 0.000 abstract description 14
- 238000006243 chemical reaction Methods 0.000 abstract description 7
- 230000001376 precipitating effect Effects 0.000 abstract 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 87
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 54
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 240000007594 Oryza sativa Species 0.000 description 2
- 235000007164 Oryza sativa Nutrition 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 2
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
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- 244000276331 Citrus maxima Species 0.000 description 1
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- 239000003990 capacitor Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
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- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/312—Preparation
- C01B32/342—Preparation characterised by non-gaseous activating agents
- C01B32/348—Metallic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
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- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/312—Preparation
- C01B32/318—Preparation characterised by the starting materials
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0003—General processes for their isolation or fractionation, e.g. purification or extraction from biomass
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0006—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid
- C08B37/0057—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid beta-D-Xylans, i.e. xylosaccharide, e.g. arabinoxylan, arabinofuronan, pentosans; (beta-1,3)(beta-1,4)-D-Xylans, e.g. rhodymenans; Hemicellulose; Derivatives thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
- B01D2253/10—Inorganic adsorbents
- B01D2253/102—Carbon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/708—Volatile organic compounds V.O.C.'s
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
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Abstract
The invention discloses a method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction, and high-proportion microporous activated carbon and application thereof. The method comprises the following steps: performing alkali extraction, solid-liquid separation on a fiber raw material, precipitating a filtrate by ethanol to obtain hemicellulose, washing and drying a solid residue to obtain a pre-extracted raw material, carbonizing the pre-extracted raw material under inert gas to obtain carbonized solid, mixing the carbonized solid with an activating agent into water, activating the carbonized solid under the inert gas after drying, and then washing and drying the carbonized solid to obtain the high-proportion microporous active carbon. The invention realizes the high conversion utilization of hemicellulose in biomass, maintains the carbon output and obviously improves the micropores of the prepared active carbonThe specific surface area and pore volume, the micropore specific surface area is increased to 2039-2446 m 2 And/g, 52.5-77.6% improvement, micropores are used as VOCs adsorption sites, and high adsorption capacity is brought by high proportion of micropores. The invention improves the adsorption performance of the activated carbon VOCs and the resource utilization rate at the same time.
Description
Technical Field
The invention belongs to the technical field of biomass refining and biomass activated carbon preparation, and particularly relates to a method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction, the high-proportion microporous activated carbon and application thereof.
Background
The active carbon is used as a carbonaceous material with developed pore structure, large specific surface area, abundant surface chemical groups and strong specific adsorption capacity, is widely applied to the fields of traditional foods, light industry, medicines, military industry, chemical industry and the like, and also is developed to the high and new technological fields such as environmental protection, energy storage, nano materials, aerospace, bioengineering and the like along with the enhancement of environmental protection, the rising of new energy sources, the development of nano materials and the like in recent years. The market demand of activated carbon is continuously increasing, and the activated carbon is an essential material in modern industry, ecological protection and people's life.
The raw materials for preparing the activated carbon comprise various carbonaceous materials such as coal, stone tar, biomass raw materials and the like. At present, coal is a main raw material for preparing activated carbon, but the coal belongs to non-renewable energy sources, and along with rapid consumption of coal resources and serious environmental problems, a substitute of the coal resources is urgently needed. Biomass becomes an important raw material for preparing activated carbon because of the advantages of high carbon content, low price, large supply amount, environmental friendliness, reproducibility and the like. Most commonly used are plant fiber raw materials such as wood, wood dust and the like, and various agricultural and forestry byproducts and agricultural wastes including bamboo, bark, fruit shells, fruit pits, bagasse, rice hulls, shaddock peels and the like, and the biomass raw materials can be subjected to high-temperature treatment to obtain the carbon-rich material. The method utilizes agricultural waste biomass raw materials such as straw, miscanthus, pericarp and the like to prepare the carbon electrode material for the super capacitor by a simple and rapid method, but the specific surface area of the activated carbon prepared by the granted patent is smaller. The method takes wood chips and bamboo chips as raw materials and phosphoric acid as an activating agent, and the biomass activated carbon with concentrated pore size distribution and high strength is prepared through low-temperature pre-pyrolysis and raw material ultrafining. However, the issued patent will cause significant pyrolysis of hemicellulose during the pre-pyrolysis of the feedstock, resulting in the loss of hemicellulose from the feedstock. Biomass activated carbon, particularly activated carbon prepared from plant fibers, has many advantages, but tends to have low yield in actual production. The main components of the plant fiber raw material are cellulose, hemicellulose and lignin, and the three components can be decomposed at different rates in different temperature ranges in the preparation process of the activated carbon, wherein the hemicellulose is most susceptible to thermal decomposition, so that the conversion utilization rate of the hemicellulose in the preparation process of the activated carbon from the plant fiber raw material is low, the mass pyrolysis of the hemicellulose in the actual carbon preparation process leads to low contribution rate to the quality of the activated carbon, the carbon yield of the plant fiber raw material is reduced, the resource waste is caused, and carbon-containing volatile components such as carbon monoxide, carbon dioxide, methane and the like can be generated. Therefore, hemicellulose which is most easily thermally decomposed in the plant fiber raw material is pre-extracted, the ineffective loss of the hemicellulose in the charcoal making process is reduced, the high conversion utilization of the hemicellulose in biomass is realized, and the method has a very positive effect.
Volatile Organic Compounds (VOCs) are defined by the world health organization as organic compounds having a saturation vapor pressure above 133.322Pa at room temperature and a boiling point between 50℃and 260 ℃. VOCs have toxicity, strong irritation, teratogenic, oncogenic and mutagenic effects, are important precursors of photochemical smog and haze, and have great harm to human body health and environment. Activated carbon is a commonly used VOCs adsorbent, and researches prove that micropores (pores with the pore diameter of less than 2 nm) in the activated carbon are main adsorption sites of the VOCs. Therefore, it is significant to increase the adsorption of VOCs by increasing the micropore specific surface area and pore volume of the biomass activated carbon.
Disclosure of Invention
Aiming at the problems of low hemicellulose conversion utilization rate and small specific surface area of activated carbon in the preparation process of biomass activated carbon in the prior art, the primary aim of the invention is to provide a method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction, so that the high conversion utilization of hemicellulose in biomass is realized, and the micropore specific surface area and pore volume of the prepared activated carbon are obviously improved while the carbon yield is maintained.
It is another object of the present invention to provide the high proportion microporous activated carbon prepared based on hemicellulose pre-extraction.
It is a further object of the present invention to provide the use of high proportions of microporous activated carbon for the adsorption and separation of VOCs.
The aim of the invention is achieved by the following technical scheme:
the invention provides a method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction, which comprises the following steps:
(1) Hemicellulose pre-extraction: adding the fiber raw material into an alkali solution for extraction, and carrying out solid-liquid separation to obtain filtrate (hemicellulose solution) and solid residues; adding an organic solvent into the filtrate, standing, centrifuging, washing, and drying to obtain hemicellulose; washing and drying the solid residues to obtain hemicellulose pre-extracted fiber raw materials serving as carbon precursors;
(2) Carbonizing: placing the carbon precursor in the step (1) in a tube furnace for carbonization treatment under inert gas to obtain carbonized solid;
(3) Activating: mixing the carbonized solid in the step (2) with an activating agent, adding the mixture into water, stirring and mixing uniformly, and then drying the mixture in an oven at 105-120 ℃ to obtain a solid mixture of the carbonized solid and the activating agent; placing the solid mixture into a tube furnace for activation treatment under inert gas to obtain an activated product;
(4) Immersing the activated product obtained in the step (3) into an acid solution, stirring and mixing uniformly, standing, washing with water until the filtrate is neutral, and drying to obtain the high-proportion microporous activated carbon.
Further, the fiber raw material in the step (1) is a raw material rich in hemicellulose, and comprises more than one of broad-leaved wood, needle-leaved wood, non-wood rice hulls, non-wood corncobs and non-wood straws.
Further, in the step (1), the fiber raw material is one or more of a hardwood raw material and a softwood raw material.
Further, the mass percentage of hemicellulose in the broad-leaved wood raw material is 20% -35%; the mass percentage of hemicellulose in the needle leaf material is 15-25%.
Further, the fiber raw material in the step (1) is a pretreated fiber raw material, and the pretreatment is realized by the following steps: and (3) air-drying the wood chips, crushing, sieving by a standard inspection sieve, and finally drying in an oven at 105-120 ℃ to obtain the pretreated absolute dry fiber raw material.
Further, the air drying time is 1-3 days; the crushing is performed by adopting a biomass crusher; the mesh number of the standard inspection sieve is 40-60 meshes; drying in the oven for 24-36 h.
Further, the alkali solution in the step (1) is a LiOH solution, naOH solution or KOH solution.
Further, the alkali solution in the step (1) is a KOH solution.
Further, the alkali solution in the step (1) is an alkali solution with the concentration of 4-20wt%.
Further, the ratio of the mass of the fiber raw material to the volume of the alkali solution in the step (1) is 1kg to (5-15) L
Further, the ratio of the mass of the fiber raw material to the volume of the alkali solution in the step (1) is 1 kg:10L
Further, the extraction time in the step (1) is 1 to 3 hours,
further, the extraction time in step (1) was 3 hours.
Further, the temperature of the extraction in the step (1) is 25-35 ℃.
Further, in the step (1), the solid-liquid separation is performed by adopting a hydraulic vacuum pump and a G2 sand core funnel.
Further, in the step (1), the organic solvent is at least one of ethanol solution and acetone.
Further, in the step (1), the organic solvent is absolute ethanol.
Further, the volume ratio of the filtrate to the organic solvent in the step (1) is 1:2-3.
Further, the volume ratio of the filtrate to the organic solvent in the step (1) is 1:3.
Further, the rotational speed of the centrifugation in the step (1) is 8000-12000 r/min.
Further, the hemicellulose drying conditions in step (1) are: vacuum drying in a vacuum drying oven at 40-50 deg.c for 24-36 hr.
Further, the hemicellulose drying conditions in step (1) are: vacuum drying in a vacuum drying oven at 45 deg.C for 36 hr,
further, the drying conditions of the solid residue in the step (1) are as follows: drying in an oven at 105-120 ℃ for 12-24 h. Further, in the step (2) and the step (3), the inert gas is one or more of nitrogen with a purity of 99% or more and argon with a purity of 99% or more, and the flow rate of the inert gas is 200-400 mL/min.
Further, the flow rate of the inert gas in the step (2) and the step (3) is 300mL/min.
Further, the heating rate of the carbonization treatment in the step (2) and the activation treatment in the step (3) is 5-15 ℃/min.
Further, the conditions of the carbonization treatment in the step (2) are as follows: the carbonization treatment temperature is 450-550 ℃, and the carbonization treatment time is 40-80 min.
Further, the conditions of the carbonization treatment in the step (2) are as follows: the carbonization temperature is 500 ℃, and the carbonization time is 60min.
Further, the activator in the step (3) is KOH, K 2 CO 3 Or KHCO 3 More than one of them.
Further, in the step (3), the activator is KOH.
Further, the mass ratio of the carbonized solid to the activator in the step (3) is 1:2-4 based on dry weight.
Further, the mass ratio of the carbonized solid to the activator in the step (3) is 1:4 based on dry weight.
Further, the conditions of the activation treatment in the step (3) are as follows: the activation treatment temperature is 750-850 ℃, the activation treatment time is 40-80 min,
further, the conditions of the activation treatment in the step (3) are as follows: the activation treatment temperature is 800 ℃, and the activation treatment time is 60min.
Further, the acid solution in the step (4) is hydrochloric acid with the concentration of 1-6M.
Further, the acid solution in the step (4) is hydrochloric acid with the concentration of 1M.
Further, the standing time in the step (4) is 6-12 hours.
Further, the drying conditions in the step (4) are as follows: drying in an oven at 105-120 ℃ for 12-24 h.
The invention provides high-proportion microporous activated carbon prepared by the preparation method.
Further, the high proportion of microporous activated carbon has a high specific surface area.
The invention also provides application of the high-proportion microporous activated carbon prepared based on hemicellulose pre-extraction in adsorption and separation of VOCs.
Furthermore, the method for preparing the high-proportion microporous activated carbon based on hemicellulose pre-extraction can remarkably improve the adsorption capacity of the prepared high-proportion microporous activated carbon material on VOCs.
According to the method for preparing the high-proportion microporous activated carbon based on hemicellulose pre-extraction, the high conversion and utilization of hemicellulose in biomass are realized, the hemicellulose is obtained, the carbon yield is maintained, and the specific surface area, the total pore volume, the micropore specific surface area, the micropore volume and other pore structure parameters of the prepared activated carbon are obviously improved.
The specific surface area of the high-proportion microporous active carbon prepared by the preparation method is 2458-3066 m 2 Per gram, the micropore specific surface area is 2039-2446 m 2 Per gram, the total pore volume is 1.00-1.32 cm 3 Per gram, the micropore volume is 0.81-1.00 cm 3 /g。
Compared with the prior art, the invention has the following advantages and effects:
1. the invention provides a novel method for preparing high-performance activated carbon by pre-extracting semi-fibers. The hemicellulose pre-extraction step of the invention removes 15-25% of components in the fiber raw material by mass percent, the components are mainly hemicellulose which is easy to be thermally decomposed, the yield of the activated carbon prepared from the fiber raw material prepared by hemicellulose pre-extraction is only reduced by 1-2% compared with the yield of the activated carbon prepared from the fiber raw material without hemicellulose pre-extraction, the total yield of the high-proportion microporous activated carbon prepared by the invention is not obviously affected, and the change of the yield of the high-proportion microporous activated carbon is less than the change of the total amount of the fiber raw material caused by hemicellulose extraction (namely, the components with mass percent of 15-25% in the fiber raw material are removed). The hemicellulose which is mainly used as volatile matters to escape in the preparation process of the activated carbon is dissolved out in advance, and on the premise that the total weight of the raw materials is reduced by 15% -25%, the higher activated carbon yield of the fiber raw materials is pre-extracted through the hemicellulose, so that the total yield of the activated carbon is maintained similar to that of the prior activated carbon, and the utilization rate of carbon sources is improved.
2. According to the invention, biomass refining and activated carbon preparation are combined, hemicellulose is obtained while the preparation of the activated carbon is not influenced, the invalid loss of the hemicellulose in the carbon preparation process is reduced, the high conversion utilization of the hemicellulose in biomass is realized, and the hemicellulose can be applied to various fields such as chemistry, food, papermaking, energy sources, pharmacy and the like. The KOH which is used as a pretreatment agent can be recovered simultaneously when hemicellulose is obtained, and the KOH is used as the pretreatment agent in the pretreatment process and the activator in the preparation process of the activated carbon. The high added value of the extracted hemicellulose and the reusability of potassium hydroxide improve the resource utilization level of the whole process, reduce waste and reduce cost.
3. According to the invention, the fiber raw material is treated by alkali pre-extraction, partial components are removed to increase the porosity of the raw material, the permeation and diffusion functions of the fiber cell layer are enhanced, the fiber raw material becomes easier to permeate, a foundation is provided for better permeation of an activating agent, and the pre-extraction of hemicellulose remarkably improves the specific surface area, the total pore volume, the micropore specific surface area, the micropore pore volume and other pore structure parameters of the prepared activated carbon. The micropores serve as main adsorption sites of VOCs, and a high proportion of micropores bring about higher adsorption capacity of VOCs. The excellent physical and chemical properties and pore structure of the nano-porous material can be applied to the fields of traditional foods, light industry, medicines, chemical industry and the like, and can be widely applied to the high and new technology fields of environmental protection, new energy sources, new nano-materials and the like.
4. The raw materials adopted by the invention are wide in sources and low in cost, the hemicellulose extraction process and the activated carbon preparation method are simple to operate, the conditions are easy to control, chemicals in the production process can be recycled, the preparation cost is reduced, and the large-scale industrial production is easy to realize.
Drawings
FIG. 1 is a flow chart of a process for preparing the high-proportion microporous activated carbon.
FIG. 2 is a nitrogen adsorption/desorption isotherm plot of the high proportion of microporous activated carbon prepared in example 1-2 and the activated carbon prepared in comparative example 1-2.
FIG. 3 is a graph showing pore size distribution of the high proportion of microporous activated carbon prepared in example 1-2 and the activated carbon prepared in comparative example 1-2.
FIG. 4 is a graph showing the dynamic adsorption of toluene by the high proportion of microporous activated carbon prepared in example 1-2 and the activated carbon prepared in comparative example 1-2.
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the present invention are not limited thereto. It should be noted that the experimental methods not specifically described in the following examples are all conventional methods in the art. Unless otherwise specified, the reagents or equipment used in the present invention are conventional products which can be purchased commercially.
FIG. 1 is a flow chart of a process for preparing the high-proportion microporous activated carbon.
The broad-leaved wood raw material and the needle-leaved wood raw material related to the embodiment of the invention can be obtained through market, the mass percentage of hemicellulose of the broad-leaved wood raw material is 20% -35%, and the mass percentage of hemicellulose of the needle-leaved wood raw material is 15% -25%.
The raw materials are firstly crushed and screened for pretreatment: air-drying raw wood chips for 3 days, crushing by a biomass crusher, sieving by a 40-60 target standard inspection sieve, and finally drying in an oven at 105 ℃ for 24 hours to prepare the absolute dry powder fiber raw material.
Example 1
(1) Hemicellulose pre-extraction: taking 10G of absolute dry powdery broad-leaved wood fiber raw material, adding the raw material into a 20wt% KOH aqueous solution at 30 ℃ for extraction for 3 hours according to a feed-liquid ratio of 1:10, and carrying out solid-liquid separation by using a hydraulic vacuum pump and a G2 sand core funnel to obtain filtrate (hemicellulose solution) and solid residues; dispersing 100mL of filtrate in 300mL of absolute ethyl alcohol, standing to precipitate, removing two thirds of the volume of supernatant, centrifuging the rest solid-liquid mixture in a centrifuge of 12000r/min, washing again, repeating the centrifuging and washing processes for 3 times, and vacuum drying in a vacuum drying oven at 45 ℃ for 36h to obtain hemicellulose; filtering and washing the solid residues with ultrapure water until the filtrate is neutral, and drying the solid residues in an oven at 105 ℃ for 24 hours to obtain hemicellulose pre-extracted broadleaf fiber raw materials which are used as carbon precursors, wherein the yield of the hemicellulose pre-extracted broadleaf fiber raw materials is 76.5 percent relative to the absolute dry powder broadleaf fiber raw materials.
(2) Carbonizing: and (3) placing the carbon precursor in the step (1) in a tube furnace, heating to 500 ℃ for carbonization for 60min at a heating rate of 10 ℃/min under argon gas with a flow rate of 300mL/min, and naturally cooling to room temperature to obtain carbonized solid.
(3) Activating: adding the carbonized solid obtained in the step (2) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 800 ℃ under argon gas with the flow rate of 300mL/min at the heating rate of 10 ℃/min, activating for 60min, and naturally cooling to room temperature to obtain an activated product.
(4) Immersing the activated product obtained in the step (3) into 1M hydrochloric acid, stirring and mixing uniformly, standing for 12h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 24h to obtain the high-proportion microporous activated carbon. The yield of the high-proportion microporous activated carbon is 16.5 percent relative to the absolute dry type broad-leaved wood fiber raw material.
FIG. 2 shows the nitrogen adsorption/desorption isotherm of the high proportion of microporous activated carbon prepared in example 1, and FIG. 3 shows the high proportion prepared in example 1Pore size distribution of the proportional microporous activated carbon. The specific surface area is 2458m by calculation 2 Per gram, micropore specific surface area of 2298m 2 Per gram, a total pore volume of 1.01cm 3 Per gram, micropore volume of 0.91cm 3 The specific surface area of micropores accounts for 93.5 percent of the total specific surface area, the pore volume of micropores accounts for 90.1 percent of the total pore volume, and the activated carbon is provided with high proportion of micropores. FIG. 4 shows the toluene dynamic adsorption curve of the high proportion microporous activated carbon prepared in example 1, and the toluene dynamic adsorption capacity thereof is 711mg/g by calculation.
Example 2
(1) Hemicellulose pre-extraction: taking 10G of absolute dry powder needle-leaf fiber raw material, adding the raw material into a 20wt% KOH aqueous solution at 30 ℃ for extraction for 3 hours according to a feed-liquid ratio of 1:10, and carrying out solid-liquid separation by using a hydraulic vacuum pump and a G2 sand core funnel to obtain filtrate (hemicellulose solution) and solid residues; dispersing 100mL of filtrate in 300mL of absolute ethyl alcohol, standing to precipitate, removing two thirds of the volume of supernatant, centrifuging the rest solid-liquid mixture in a centrifuge of 12000r/min, washing again, repeating the centrifuging and washing processes for 3 times, and vacuum drying in a vacuum drying oven at 45 ℃ for 36h to obtain hemicellulose; filtering and washing the solid residues with ultrapure water until the filtrate is neutral, and drying the solid residues in an oven at 105 ℃ for 24 hours to obtain the hemicellulose pre-extracted needle-leaf fiber raw material which is used as a carbon precursor, wherein the yield of the hemicellulose pre-extracted needle-leaf fiber raw material is 90.7 percent relative to the absolute dry powder needle-leaf fiber raw material.
(2) Carbonizing: and (3) placing the carbon precursor in the step (1) in a tube furnace, heating to 500 ℃ for carbonization for 60min at a heating rate of 10 ℃/min under argon gas with a flow rate of 300mL/min, and naturally cooling to room temperature to obtain carbonized solid.
(3) Activating: adding the carbonized solid obtained in the step (2) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 800 ℃ under argon gas with the flow rate of 300mL/min at the heating rate of 10 ℃/min, activating for 60min, and naturally cooling to room temperature to obtain an activated product.
(4) Immersing the activated product obtained in the step (3) into 1M hydrochloric acid, stirring and mixing uniformly, standing for 12h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 24h to obtain the high-proportion microporous activated carbon. The yield of the high-proportion microporous activated carbon is 20.7 percent relative to the absolute dry powder needle-leaf fiber raw material.
Fig. 2 shows a nitrogen adsorption/desorption isothermal curve of the high proportion microporous activated carbon prepared in example 2, and fig. 3 shows a pore size distribution of the high proportion microporous activated carbon prepared in example 2. The specific surface area is 2682m by calculation 2 Per gram, micropore specific surface area of 2446m 2 Per gram, a total pore volume of 1.14cm 3 Per gram, a micropore volume of 1.00cm 3 The specific surface area of micropores accounts for 91.2 percent of the total specific surface area, the pore volume of micropores accounts for 87.7 percent of the total pore volume, and the activated carbon is provided with high proportion of micropores. FIG. 4 shows the toluene dynamic adsorption curve of the high proportion microporous activated carbon prepared in example 2, and the toluene dynamic adsorption capacity thereof is 718mg/g by calculation.
Example 3
(1) Hemicellulose pre-extraction: taking 10G of absolute dry powdery broad-leaved wood fiber raw material, adding the raw material into a 4wt% KOH aqueous solution at 25 ℃ for extraction for 1h according to a feed-liquid ratio of 1:15, and carrying out solid-liquid separation by using a hydraulic vacuum pump and a G2 sand core funnel to obtain filtrate (hemicellulose solution) and solid residues; dispersing 150mL of filtrate in 300mL of absolute ethyl alcohol, standing to precipitate, removing two thirds of the volume of supernatant, centrifuging the rest solid-liquid mixture in a centrifugal machine of 8000r/min, washing, repeating the centrifuging and washing processes for 3 times, and vacuum drying in a vacuum drying oven at 50 ℃ for 24 hours to obtain hemicellulose; filtering and washing the solid residues with ultrapure water until the filtrate is neutral, and drying in an oven at 120 ℃ for 12 hours to obtain hemicellulose pre-extracted broadleaf fiber raw materials which are used as carbon precursors, wherein the yield of the hemicellulose pre-extracted broadleaf fiber raw materials is 85.7 percent relative to the absolute dry powder broadleaf fiber raw materials.
(2) Carbonizing: and (3) placing the carbon precursor in the step (1) in a tube furnace, heating to 450 ℃ in a heating rate of 5 ℃/min under nitrogen gas with a flow rate of 200mL/min, carbonizing for 60min, and naturally cooling to room temperature to obtain carbonized solid.
(3) Activating: adding the carbonized solid obtained in the step (2) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 850 ℃ at a heating rate of 5 ℃/min under nitrogen gas with a flow rate of 200mL/min, activating for 60min, and naturally cooling to room temperature to obtain an activated product.
(4) Immersing the activated product obtained in the step (3) into 6M hydrochloric acid, stirring and mixing uniformly, standing for 6h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 12h to obtain the high-proportion microporous activated carbon. The yield of the high-proportion microporous activated carbon is 16.4 percent relative to the absolute dry type broad-leaved wood fiber raw material.
The nitrogen adsorption/desorption isothermal curve of the high-proportion microporous activated carbon prepared in example 3 is calculated to obtain the specific surface area of 2500m 2 Per gram, micropore specific surface area of 2039m 2 Per gram, a total pore volume of 1.06cm 3 Per gram, a micropore volume of 0.81cm 3 The specific surface area of micropores accounts for 81.6 percent of the total specific surface area, the pore volume of micropores accounts for 76.4 percent of the total pore volume, and the activated carbon is provided with high proportion of micropores. The toluene dynamic adsorption capacity of the high-proportion microporous activated carbon prepared in example 3 is calculated to be 673mg/g according to the toluene dynamic adsorption curve.
Example 4
(1) Hemicellulose pre-extraction: taking 10G of absolute dry powdery broad-leaved wood fiber raw material, adding the raw material into 10wt% KOH aqueous solution at 30 ℃ for extraction for 1h according to the feed-liquid ratio of 1:5, and carrying out solid-liquid separation by using a hydraulic vacuum pump and a G2 sand core funnel to obtain filtrate (hemicellulose solution) and solid residues; dispersing 50mL of filtrate in 150mL of absolute ethyl alcohol, standing to precipitate, removing two thirds of the volume of supernatant, centrifuging the rest solid-liquid mixture in a 10000r/min centrifuge, washing again, repeating the centrifuging and washing processes for 3 times, and vacuum drying in a vacuum drying oven at 40 ℃ for 30 hours to obtain hemicellulose; filtering and washing the solid residues with ultrapure water until the filtrate is neutral, and drying the solid residues in an oven at 115 ℃ for 18 hours to obtain the hemicellulose pre-extracted broadleaf fiber raw material which is taken as a carbon precursor, wherein the yield of the hemicellulose pre-extracted broadleaf fiber raw material is 79.9 percent relative to the absolute dry powder broadleaf fiber raw material.
(2) Carbonizing: and (3) placing the carbon precursor in the step (1) in a tube furnace, heating to 500 ℃ for carbonization for 40min at a heating rate of 10 ℃/min under nitrogen gas with a flow rate of 300mL/min, and naturally cooling to room temperature to obtain carbonized solid.
(3) Activating: adding the carbonized solid obtained in the step (2) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 800 ℃ at a heating rate of 10 ℃/min under nitrogen gas with a flow rate of 300mL/min, activating for 80min, and naturally cooling to room temperature to obtain an activated product.
(4) Immersing the activated product obtained in the step (3) into 5M hydrochloric acid, stirring and mixing uniformly, standing for 10h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 18h to obtain the high-proportion microporous activated carbon. The yield of the high-proportion microporous activated carbon is 16.5 percent relative to the absolute dry type broad-leaved wood fiber raw material.
The specific surface area of the high-proportion microporous activated carbon prepared in example 4 was 2478m by calculation from the nitrogen adsorption/desorption isothermal curve 2 Per gram, micropore specific surface area of 2248m 2 Per gram, a total pore volume of 1.00cm 3 Per gram, micropore volume of 0.87cm 3 The specific surface area of micropores accounts for 90.7% of the total specific surface area, the pore volume of micropores accounts for 87.0% of the total pore volume, and the activated carbon is provided with high proportion of micropores. The toluene dynamic adsorption capacity of the high-proportion microporous activated carbon prepared in example 4 is 693mg/g.
Example 5
(1) Hemicellulose pre-extraction: taking 10G of absolute dry powdery broad-leaved wood fiber raw material, adding the raw material into a 4wt% KOH aqueous solution at 35 ℃ for extraction for 3 hours according to a feed-liquid ratio of 1:10, and carrying out solid-liquid separation by using a hydraulic vacuum pump and a G2 sand core funnel to obtain filtrate (hemicellulose solution) and solid residues; dispersing 100mL of filtrate in 200mL of absolute ethyl alcohol, standing to precipitate, removing two-thirds volume of supernatant, centrifuging the rest solid-liquid mixture in a centrifuge of 12000r/min, washing, repeating the centrifuging and washing processes for 3 times, and vacuum drying in a vacuum drying oven at 40 ℃ for 36h to obtain hemicellulose; filtering and washing the solid residues with ultrapure water until the filtrate is neutral, and drying in an oven at 110 ℃ for 24 hours to obtain hemicellulose pre-extracted broadleaf fiber raw materials which are used as carbon precursors, wherein the yield of the hemicellulose pre-extracted broadleaf fiber raw materials is 84.5% relative to the absolute powder broadleaf fiber raw materials.
(2) Carbonizing: and (3) placing the carbon precursor in the step (1) in a tube furnace, heating to 550 ℃ in the argon gas with the flow rate of 400mL/min at the heating rate of 5 ℃/min, carbonizing for 60min, and naturally cooling to room temperature to obtain carbonized solid.
(3) Activating: adding the carbonized solid obtained in the step (2) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 750 ℃ under argon gas with the flow rate of 400mL/min at the heating rate of 5 ℃/min, activating for 60min, and naturally cooling to room temperature to obtain an activated product.
(4) Immersing the activated product obtained in the step (3) into 3M hydrochloric acid, stirring and mixing uniformly, standing for 10h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 24h to obtain the high-proportion microporous activated carbon. The yield of the high-proportion microporous activated carbon is 16.9 percent relative to the absolute dry type broad-leaved wood fiber raw material.
The specific surface area of the high-proportion microporous activated carbon prepared in example 5 is 3066m by calculation according to the nitrogen adsorption/desorption isothermal curve 2 Per gram, micropore specific surface area of 2374m 2 Per gram, a total pore volume of 1.32cm 3 Per gram, a micropore volume of 0.95cm 3 Per gram, the micropore specific surface area accounts for 77.4 percent of the total specific surface area, the micropore volume accounts for 72.0 percent of the total pore volume, is a high proportionMicroporous activated carbon. The toluene dynamic adsorption capacity of the high-proportion microporous activated carbon prepared in example 5 was calculated to be 737mg/g according to the toluene dynamic adsorption curve.
Example 6
(1) Hemicellulose pre-extraction: taking 10G of absolute dry powdery broad-leaved wood fiber raw material, adding the raw material into 10wt% KOH aqueous solution at 30 ℃ for extraction for 3 hours according to the feed-liquid ratio of 1:10, and carrying out solid-liquid separation by using a hydraulic vacuum pump and a G2 sand core funnel to obtain filtrate (hemicellulose solution) and solid residues; dispersing 100mL of filtrate in 300mL of absolute ethyl alcohol, standing to precipitate, removing two thirds of the volume of supernatant, centrifuging the rest solid-liquid mixture in a centrifuge of 12000r/min, washing again, repeating the centrifugation and washing processes for 3 times, and vacuum drying in a vacuum drying oven at 50 ℃ for 36h to obtain hemicellulose; filtering and washing the solid residues with ultrapure water until the filtrate is neutral, and drying in an oven at 120 ℃ for 12 hours to obtain hemicellulose pre-extracted broadleaf fiber raw materials which are used as carbon precursors, wherein the yield of the hemicellulose pre-extracted broadleaf fiber raw materials is 79.0 percent relative to the absolute dry powder broadleaf fiber raw materials.
(2) Carbonizing: and (3) placing the carbon precursor in the step (1) in a tube furnace, heating to 500 ℃ in the argon gas with the flow rate of 300mL/min at the heating rate of 15 ℃/min, carbonizing for 80min, and naturally cooling to room temperature to obtain carbonized solid.
(3) Activating: adding the carbonized solid obtained in the step (2) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 800 ℃ under argon gas with the flow rate of 300mL/min at the heating rate of 15 ℃/min, activating for 40min, and naturally cooling to room temperature to obtain an activated product.
(4) Immersing the activated product obtained in the step (3) into 2M hydrochloric acid, stirring and mixing uniformly, standing for 12h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 12h to obtain the high-proportion microporous activated carbon. The yield of the high-proportion microporous activated carbon is 16.7 percent relative to the absolute dry type broad-leaved wood fiber raw material.
The nitrogen adsorption/desorption isothermal curve of the high-proportion microporous activated carbon prepared in example 6 is calculated to obtain the specific surface area of 2500m 2 Per gram, micropore specific surface area 2221m 2 Per gram, a total pore volume of 1.02cm 3 Per gram, micropore volume of 0.87cm 3 The specific surface area of micropores accounts for 88.8 percent of the total specific surface area, the pore volume of micropores accounts for 85.3 percent of the total pore volume, and the activated carbon is provided with high proportion of micropores. The toluene dynamic adsorption capacity of the high-proportion microporous activated carbon prepared in example 6 is calculated to be 684mg/g according to the toluene dynamic adsorption curve.
Comparative example 1
(1) Carbonizing: taking 10g of absolute dry powder broadleaf fiber raw material as a carbon precursor, placing the carbon precursor into a tube furnace, heating to 500 ℃ at a heating rate of 10 ℃/min under argon gas with a flow rate of 300mL/min, carbonizing for 60min, and naturally cooling to room temperature to obtain carbonized solid.
(2) Activating: adding the carbonized solid obtained in the step (1) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 800 ℃ under argon gas with the flow rate of 300mL/min at the heating rate of 10 ℃/min, activating for 60min, and naturally cooling to room temperature to obtain an activated product.
(3) Immersing the activated product obtained in the step (2) into 1M hydrochloric acid, stirring and mixing uniformly, standing for 12h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 24h to obtain the activated carbon of the comparative example 1. The yield of the activated carbon is 18.0 percent relative to the absolute dry type broad-leaved wood fiber raw material.
Fig. 2 shows a nitrogen adsorption/desorption isothermal curve of the activated carbon prepared in comparative example 1, and fig. 3 shows a pore size distribution of the activated carbon prepared in comparative example 1. The specific surface area is 1401m by calculation 2 Per gram, micropore specific surface area of 1337m 2 Per gram, a total pore volume of 0.59cm 3 Per gram, micropore volume of 0.51cm 3 Per gram, the micropore specific surface area accounts for 95.4% of the total specific surface area, and the micropore volume accounts for 86.4% of the total pore volume. Drawing of the figure4 shows the toluene dynamic adsorption curve of the activated carbon prepared in comparative example 1, and the toluene dynamic adsorption capacity thereof is 378mg/g by calculation.
By comparison of example 1 and comparative example 1, the hemicellulose pre-extraction step of example 1 of the present invention removes 23.5% of the components of the hardwood fiber feedstock, the components removed being primarily hemicellulose. Compared with the non-extracted hemicellulose raw material, the high-proportion microporous activated carbon prepared from the hemicellulose pre-extracted broad-leaved wood fiber raw material has the advantages that the yield is reduced only slightly, but the high-proportion microporous activated carbon shows a more excellent pore structure, the total specific surface area is improved by 75.4%, the microporous specific surface area is improved by 71.9%, and the toluene adsorption capacity is improved by 88.1%.
Comparative example 2
(1) Carbonizing: taking 10g of absolute dry powder needle-leaf fiber raw material as a carbon precursor, placing the carbon precursor into a tube furnace, heating to 500 ℃ at a heating rate of 10 ℃/min under argon gas with a flow rate of 300mL/min, carbonizing for 60min, and naturally cooling to room temperature to obtain carbonized solid.
(2) Activating: adding the carbonized solid obtained in the step (1) and KOH into 200mL of ultrapure water after blending according to the mass ratio of 1:4, stirring and uniformly mixing, and then drying in an oven at 105 ℃ to obtain a solid mixture of the carbonized solid and KOH; and (3) placing the solid mixture in a tube furnace, heating to 800 ℃ under argon gas with the flow rate of 300mL/min at the heating rate of 10 ℃/min, activating for 60min, and naturally cooling to room temperature to obtain an activated product.
(3) Immersing the activated product obtained in the step (2) into 1M hydrochloric acid, stirring and mixing uniformly, standing for 12h, washing with water until the filtrate is neutral, and drying in an oven at 105 ℃ for 24h to obtain the activated carbon of the comparative example 2. The yield of the activated carbon is 18.7 percent relative to the absolute dry powder needle-leaf fiber raw material.
Fig. 2 shows a nitrogen adsorption/desorption isothermal curve of the activated carbon prepared in comparative example 2, and fig. 3 shows a pore size distribution of the activated carbon prepared in comparative example 2. The specific surface area is 1540m by calculation 2 Per gram, micropore specific surface area of 1461m 2 Per gram, a total pore volume of 0.65cm 3 Per gram, micropore volume of 0.56cm 3 Per gram, the micropore specific surface area is the totalThe specific surface area was 94.9% and the micropore volume was 86.2% of the total pore volume. FIG. 4 shows the toluene dynamic adsorption curve of the activated carbon prepared in comparative example 2, whose toluene dynamic adsorption capacity was 407mg/g by calculation.
By comparison of example 2 and comparative example 2, the hemicellulose pre-extraction step of example 2 of the present invention removed 9.3% of the components of the needle-leaved wood fiber raw material, the removed components being mainly hemicellulose. The high-proportion microporous activated carbon prepared from the needle-leaved material fiber raw material obtained through the hemicellulose pre-extraction step in the embodiment 2 of the invention has a slightly improved yield compared with the unextracted hemicellulose raw material, and shows a more excellent pore structure, the total specific surface area is improved by 74.2%, the microporous specific surface area is improved by 67.4%, and the toluene adsorption capacity is improved by 74.7%.
TABLE 1 activated carbon yield and primary pore Structure parameters
The yield of activated carbon in table 1 above is the yield of activated carbon relative to the oven-dried powdered fibrous raw material prior to extraction of the non-hemicellulose; s is S BET Represents a specific surface area; s is S micro Represents the specific surface area of micropores (micropores of activated carbon refer to pores with a pore diameter of less than 2 nm); v (V) total Representing the total pore volume; v (V) micro Representing micropore volume.
The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the scope of the present invention.
Claims (10)
1. The method for preparing the high-proportion microporous activated carbon based on hemicellulose pre-extraction is characterized by comprising the following steps of:
(1) Hemicellulose pre-extraction: adding the fiber raw material into an alkali solution for extraction, and carrying out solid-liquid separation to obtain filtrate and solid residues; adding an organic solvent into the filtrate, standing, centrifuging, washing, and drying to obtain hemicellulose; washing and drying the solid residues to obtain hemicellulose pre-extracted fiber raw materials serving as carbon precursors;
(2) Carbonizing: placing the carbon precursor in the step (1) in a tube furnace for carbonization treatment under inert gas to obtain carbonized solid;
(3) Activating: mixing the carbonized solid in the step (2) with an activating agent, adding the mixture into water, stirring and mixing uniformly, and then drying to obtain a solid mixture of the carbonized solid and the activating agent; placing the solid mixture into a tube furnace for activation treatment under inert gas to obtain an activated product;
(4) Immersing the activated product obtained in the step (3) into an acid solution, stirring and mixing uniformly, standing, washing with water until the filtrate is neutral, and drying to obtain the high-proportion microporous activated carbon.
2. The method for preparing high proportion of microporous activated carbon based on hemicellulose pre-extraction according to claim 1, wherein in step (1), the fiber raw material is a pretreated fiber raw material, wherein the pretreatment is achieved by: and (3) air-drying the wood chips, crushing, sieving by a standard inspection sieve, and finally drying in an oven to obtain the pretreated absolute dry fiber raw material.
3. The method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction according to claim 1, wherein the alkali solution in the step (1) is one or more of LiOH solution, naOH solution or KOH solution; the alkali solution in the step (1) is an alkali solution with the concentration of 4-20wt%; the ratio of the mass of the fiber raw material to the volume of the alkali solution in the step (1) is 1kg to (5-15) L; the extraction time in the step (1) is 1-3 h; the extraction temperature in the step (1) is 25-35 ℃; the organic solvent in the step (1) is more than one of ethanol solution or acetone; the volume ratio of the filtrate to the organic solvent in the step (1) is 1:2-3.
4. The method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction according to claim 1, wherein the rotational speed of centrifugation in step (1) is 8000-12000 r/min; the hemicellulose drying conditions in step (1) are: vacuum drying at 40-50 deg.c for 24-36 hr; the drying conditions of the solid residue in the step (1) are as follows: drying at 105-120 deg.c for 12-24 hr.
5. The method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction according to claim 1, wherein the inert gas in step (2) and step (3) is one or more of nitrogen with a purity of 99% or more or argon with a purity of 99% or more; the flow rate of the inert gas is 200-400 mL/min; the heating rate of the carbonization treatment and the activation treatment in the step (2) and the step (3) is 5-15 ℃/min.
6. The method for preparing high proportion of microporous activated carbon based on hemicellulose pre-extraction according to claim 1, wherein the condition of the carbonization treatment in step (2) is: the carbonization treatment temperature is 450-550 ℃, and the carbonization treatment time is 40-80 min.
7. The method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction as claimed in claim 1, wherein the activator in the step (3) is KOH, K 2 CO 3 Or KHCO 3 More than one of them; the mass ratio of the carbonized solid to the activator in the step (3) is 1: (2-4); the conditions of the activation treatment in the step (3) are as follows: the activation treatment temperature is 750-850 ℃, and the activation treatment time is 40-80 min.
8. The method for preparing high-proportion microporous activated carbon based on hemicellulose pre-extraction according to claim 1, wherein the acid solution in step (4) is hydrochloric acid with a concentration of 1-6M; the standing time in the step (4) is 6-12 h; the drying conditions in the step (4) are as follows: drying at 105-120 deg.c for 12-24 hr.
9. The high-proportion microporous activated carbon produced by the method for producing high-proportion microporous activated carbon based on hemicellulose pre-extraction according to any one of claims 1 to 8.
10. The use of the high proportion microporous activated carbon according to claim 9, characterized in that the high proportion microporous activated carbon is used in the adsorption and separation of VOCs.
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| CN108910876A (en) * | 2018-08-10 | 2018-11-30 | 天津科技大学 | A method of preparing activated carbon from activated sludge |
| CN109162144A (en) * | 2018-08-15 | 2019-01-08 | 华南理工大学 | A kind of preparation method and application of paper and the wet strong synergist of paper products |
| CN110937601A (en) * | 2019-12-09 | 2020-03-31 | 天津大学 | Walnut shell based activated carbon, preparation method and application thereof |
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| CN108910876A (en) * | 2018-08-10 | 2018-11-30 | 天津科技大学 | A method of preparing activated carbon from activated sludge |
| CN109162144A (en) * | 2018-08-15 | 2019-01-08 | 华南理工大学 | A kind of preparation method and application of paper and the wet strong synergist of paper products |
| CN110937601A (en) * | 2019-12-09 | 2020-03-31 | 天津大学 | Walnut shell based activated carbon, preparation method and application thereof |
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